Department of Bioengineering Instron Uniaxial Tensile Testing: Structural & Material Properties of Sutures Group 102 3B Leia Harbour Julianne Huegel Will Okech Chia-Heng Wu

Department of Bioengineering Background: Initial suture testing proved inconclusive due to small sample size and inaccurate testing procedures Larger sample size and the use of Instron technology will allow for investigation and comparison of the material properties of two suture techniques Hypothesis & Objectives: Based on raw data collected in past experiments, it is hypothesized that the horizontal mattress suture technique will have a greater failure strength and higher Young’s Modulus than the vertical mattress suture technique. Julianne Huegel

Department of Bioengineering Methods & Protocol: Sample size is ten successful sample failures for each suture technique. Measure and cut 20 samples of the CottonDuck canvas material with dimensions of 7.5 cm by 2.4 cm. Cut each of these in half crosswise. Create two groups of 10 “wound” samples and sew 4 stitches into each sample, with one population receiving horizontal mattress stitches and one population receiving vertical mattress stitches. Each stitch should be of uniform length, spacing, and distance from the edges of the sample to be determined as appropriate by the group. Insert each sample into the clamps, run Instron. Collect Stress-Strain curve data. Use a speed previously determined to be appropriate by using other materials. A speed of 60 mm/min is recommended. Use tape to minimize slippage if necessary. Save data for further analysis. Leia Harbour

Department of Bioengineering Proposed Findings: The two populations, vertical and horizontal mattress suture samples, will provide ten trials each. Each trial will produce a: 1.Stress vs. Strain Curve 2.Young’s Modulus 3.Failure Strength 4.Descriptive statistics and t-tests will be used to analyze Items 2 and 3 to investigate possible statistically significant differences between the techniques. In accordance with the hypothesis, it is expected that vertical mattress sutures will have a lower Young’s modulus and a lower failure strength based on our pilot data. Chia-Heng Wu A sample Stress-Strain curve:

Department of Bioengineering Potential Pitfalls: Inability of clamps to secure the sutured material in a fixed position resulting in slippage. Experimenter’s inability to have a constant suturing technique which could result in unequally spaced stitches. Some sutures may be tighter than others within a test sample. May experience failure in the material prior to failure of the sutures. William Okech

Department of Bioengineering Equipment, Materials and Budget The Instron will be utilized to test for the desired material properties. Needles and polyester thread are necessary for suturing two pieces of canvas together. Polyethylene tape will be provided for preventing slippage. Heavyweight canvas is used in order to limit material deformation to the suture only. To ensure suture failure, polyester thread was chosen because it’s tensile strength is less than that of other suture materials. Group 102B3 Individual Price Straight Roundpoint Needle (4 in. x 12) $15.56 Polyester Thread (diam in x 206 yds w/ 21 lb. tensile strength) $5.16 CottonDuck Canvas Fabric (0.04 in. thick x 36 in. wide) $2.08/ft *15 ft = $31.2 Polyethylene Tape (1/32 in. thick x 72 yds) $20.13 TOTAL PRICE (all mat’ls supplied by McMaster-Carr) $72.05 Materials to be Purchased: